One of the concerns in agricultural animal confinement facilities, particularly in the agricultural swine industry, is the control of the spread of disease. For example, disease agents such as mycoplasma, the swine influenza virus, and the porcine reproductive and respiratory syndrome virus (PRRSV) have had a significant negative impact on swine production. It has been estimated that PRRSV alone may increase the average cost of swine production by $5.60 to $7.62 per head.
One method that has proven effective is reducing the spread of the aforementioned disease agents is filtration of the air in animal confinement facilities. For example, high-efficiency air filters have proven to be effective at reducing the rate of airborne transmission of these disease agents. One of the challenges for the swine production industry is how to best provide the needed high-efficiency air filtration in a practical manner at the lowest cost, with ease of filter change out, and with reliability for the environmental application.
Facilities, such as those used for animal confinement, may have dozens, if not more, separate filtration units installed throughout the facility. Assembly, installation and maintenance of these filtration units is generally expensive and time-consuming. Various examples in the art are disclosed in Crabtree et al., US 2010/0313760 and Devine et al., US 2009/0301402, the entire disclosures of which are hereby incorporated by reference in their entireties. A test standard for sufficiently filtering out PRRSV is advanced in the '402 publication to Devine et al. as well as air flow requirements desired for animal confinement buildings.
Heretofore, commercially employed virus filters for animal confinement buildings (e.g. for removal of PRRSV) such as in the above examples have employed V-Bank Filters with a MERV 16 type media that is either wet laid microglass and/or synthetic polymeric fibers. V-bank filters in these applications have been used and are highly desirable due to the high flow rates experienced (e.g. typically a filter (2′ high×2′ wide) needs to handle at least 1000 CFM) as substantial air flow for hog confinement to facilitate ventilation for proper humidity, temperature and air quality (e.g. ammonia, and other airborne contaminants and byproducts of hog confinement and manure pits). The substantial header depth (e.g. filter elements are typically about 12 inches deep in the direction of air flow; also referred to as header depth) and open V shaped cavities between different filter media packs of V-Bank filters provide the capability for handling the substantial flow volume and requirements, while at the same time filtering the PRRS virus. Further, it is known to add a prefilter due to the external environment that is often laden with dust. For example pre-filters are known in combination with V-banks such as Rivera et al. U.S. Pat. No. 6,447, 566, the entire disclosure of which is hereby incorporated by reference.